A thermophilic cyanobacterium, Synechococcus sp. MA19, capable of accumulating poly-β-hydroxybutyrate

Abstract

A thermophilic cyanobacterium strain MA19 that photoautotrophically accumulates a high amount of poly-β-hydroxybutyrate (PHB) was isolated and identified as Synechococcus sp. This strain accumulated PHB at more than 20% of the dry cell weight after the cells were cultivated in a nitrogen-free inorganic medium aerated with 2% CO 2. The PHB content was the highest in all the photoautotrophic organisms. PHB was observed as intracellular granules like that previously reported for other bacteria and cyanobacteria. Supplementation of CO 2 and light intensity were effective in increasing the rate of PHB accumulation by MA19. Addition of a nitrogen source resulted in reduction of PHB content. In nitrogen-depleted dark conditions, the PHB content increased to 27% because cell weight was reduced due to glycogen decomposition. MA19 is a novel candidate for PHB production from CO 2 through a photosynthetic process.